The invention discloses a water-spray dig device of submarine cable embed machine. Wherein, a high-pressure eccentric pump driven by hydraulic motor is via bolt mounted on the rotational joint to connect the high-pressure inner tube of rotational joint the low-pressure eccentric pump driven by hydraulic motor is fixed on the frame of embedding machine and via pipeline mounted with the rotational joint and connect the low-pressure outer pipe of rotational joint one end of compression cylinder is hinged with compressor while another end is mounted on the support beam which is the base fixed and above with rotational joint two spray arms in same structure are symmetry mounted on the two sides of rotational joint while one end of one spray arm is connected to the spray cylinder and another is hinged on the rotational joint connecting the high and low pressure water line inside the rotational joint and the side-motion cylinder is mounted on the rotational joint whose piston rod is connected to the spray arms. The invention can reach standard embed depth with flexible controlled dig width and depth.